Inclination sensors are being used for continuously monitoring the angular position of movable machine components, e.g. for safety relevant components, like crane arms, man lifts and similar.
Inclination sensors are provided in various configurations.
Previously, mercury was often used for detecting the changing position of the mercury within an inclination sensor. For reasons of environmental protection, using such mercury sensors is not legal anymore for many applications.
Since then, mostly pendulum sensors are being used, thus a pendulum always lines itself up exactly vertical according to the present gravitational force, possibly dampened in that the pendulum is disposed in a damping cavity filled with damping liquid.
On the support axle of the pendulum, which extends through the pendulum cavity towards the sensor cavity, there is an angle sensitive element in the sensor cavity, whose rotation position is detected, e.g. an incremented rotating disk, which is scanned by a reading head.
The problem of this configuration is the permanently sealed passage of the pendulum shaft through the divider wall and the long-lasting ease of motion of the bearing of the pendulum axle, which facilitates a fast adjustment of the pendulum position to gravity, even for slight angular changes.
Besides that, it is known from DE 203 14 275 not to run the pendulum axle through the divider wall into the sensor cavity anymore, but to dispose a magnet on the pendulum axle within the pendulum cavity, and to detect the rotation position of the magnet contactless through the non-magnetizable divider wall through a magneto sensitive sensor, which is disposed on the opposite side in the sensor cavity.
Also here, the problem still persists that relatively high bearing forces have to be permanently received in a small central bearing axle and with very small static friction, in order to have the pendulum deflect even for the smallest angular deviations.
It is furthermore known to use singular hall elements as magneto sensitive elements, thus hall sensors, as described e.g. in the U.S. Pat. No. 5,365,671.
A single hall sensor, however, can only measure the intensity of the magnetic field, in which it is disposed, and the measurement result is thus highly dependent on the distance of the hall sensor from the encoder magnet.
Therefore, in the present case, the moving body, which aligns itself according to gravity and at which the magnet is disposed, is received in a very tightly enveloping support housing. Thus, in order to reduce the friction in the adjacent support surfaces, the cavity in which the moving body is disposed, is completely filled with a liquid, whose specific weight corresponds to the specific weight of the pivot body, so that it floats in the liquid quasi weightless (column 2, line 45 of U.S. Pat. No. 5,365,671). Thus, it is a pendulum with a center of gravity outside of the center of rotation of the pivot body, whose bearing is formed by the outer surrounding support surfaces.
Furthermore, it is known differently from that, to dispose the encoder magnet in a float. However, all these sensors only measure an angular deviation in one measurement direction.